Wrath of Khan. The rest just kind of fall into line as they will.
Ugh! I can never resist doing this. Fine! Here!
1. Wrath of Khan
2. Undiscovered Country
3. Voyage Home
4. First Contact
6. Search for Spock
8. The Motion Picture
9. Final Frontier
Yes, Nemesis is three whole spots better than Insurrection. At least until the next time I write this list, I guess. The lower five tend to drift a lot, even if the names are always the same.
XI? I think of that as a separate thing. It is the master of its own domain, if you will.